It is well known to use blister packaging to contain items such as pharmaceutical tablets or capsules. Conventional blister packages include a blister tray which is typically a thermo-formed plastic sheet having a plurality of blister depressions or cells formed therein. A lid stock is placed in overlying disposition over the blister trays to enclose the tablets contained within the individual blister depressions. The lid stock is typically sealed to the blister tray providing environmental protection thereto. The blister package provides some degree of protection to the tablets during shipping and storage and also provides for the convenient dispensing of the individual tablets from the package.
Removal of tablets from the blister package may be accomplished in one of two conventional techniques. The first technique is to provide lid stock which is supported over the blister tray in a manner where the lid stock can be easily removed from the blister tray providing ready access to the tablets contained in the blister depressions. In such embodiments the lid stock is adhesively sealed to the blister tray by a non-aggressive adhesive so that the lid stock, or a portion of the lid stock (lid) may be easily peeled from the blister tray so as to permit removal of the tablets. In such situations a non-sealed peel tab may be established adjacent one edge of the blister tray to facilitate manual peeling of the lid stock. Examples of blister packages having removable lids disposed adhesively over a blister tray are shown in U.S. Pat. Nos. 3,246,746 to Holley; 3,659,706 to Serrell; and 3,737,029 to Serrell, et al.
The second technique for permitting the removal of tablets from a blister package is to provide a readily rupturable lid stock over the blister tray. Such lid stock is formed of a laminated material which may be easily ruptured by manually deforming the blister depression and forcing the tablet through the lid stock. In such embodiments the tablet is removed from the blister package by manually pushing the blister depression and forcing the tablet held in the depression through the rupturable lid stock. The lid stock may be sufficiently thin and flexible so as to permit non-destructive passage of a conventional tablet or capsule therethrough. Examples of such push-through blister packages are shown in U.S. Pat. No. 3,924,747 to Gerner and U.S. Pat. No. 4,911,304 to Bunin.
Various other blister packages having rupturable and/or peelably removable lids are shown in U.S. Pat. Nos. 4,838,425 to O'Brien, et al. and 5,172,812 to Wharton, et al.
While the above-described techniques for storing and dispensing pharmaceutical tablets using lid stock and trays serve adequately for their intended purposes, there are certain inherent drawbacks in such designs. In both the peelable design and in the push-through design, the removal of the tablet from the package is easily accomplished. In the peelable cover design, the adhesive which holds the cover to the blister tray is relatively non-aggressive and a tab is provided which facilitates easy peelable removal of the cover from the tray. In the push-through design, the lid stock is formed of relatively thin and flexible material so as to permit the easy puncturing of the cover by the tablet without destroying the tablet.
As may be appreciated, neither of these basic designs is child entry-resistant. Thus, a child would be capable of readily dispensing the tablet from the package. Techniques have been developed to make such blister packages sufficiently child entry-resistant. However, certain of these techniques have been found to be unacceptable in certain situations. Many child resistant packages have been designed which require significant force and manual dexterity so as to render the table inaccessible to a child. Such devices however have resulted in rendering the package difficult to open even by adults. Also, specifically with respect to push-through type packages where the tablet must be forced through the lid stock, the push-through action may result in destruction of the tablet especially in situations where low density porous tablets are employed. This destruction renders the tablet useless.
It is therefore desirable to provide an improved blister package design which accommodates tablets, including low density pharmaceutical tablets where the blister package is adequately child entry-resistant and yet is simple and easy to open by an adult.